The invention relates to a measuring assembly formed by association of a current sensor with non-magnetic toroid having a first secondary winding designed to deliver a measuring signal. proportional to the derivative of the current flowing in a common primary conductor passing through an orifice, and a supply transformer comprising a magnetic circuit made of ferromagnetic material, and bearing a second secondary winding designed to supply a power supply, notably to the electronic trip device of an electrical circuit breaker.
A device of this kind is known from the document FR-A-2,599,195 filed by the applicant, in which the Rogowski toroid current sensor, and the supply transformer are arranged side by side and coaxially around the primary conductor bar. As the space set aside for the trip device in a circuit breaker case is becoming smaller and smaller, a side by side arrangement of the sensor and transformer becomes unsuitable.
The object of the invention is to reduce the size of a measuring assembly for a system-powered trip device.